Submitted to: United Fresh Produce Association
Publication Type: Abstract Only
Publication Acceptance Date: 3/12/2009
Publication Date: 4/21/2009
Citation: Beaulieu, J.C., Kuk, M.S., Mims, A.G. 2009. Extension of green bell pepper shelf life using oilseed-derived lipid films from soapstock. United Fresh Produce Association.
Technical Abstract: Edible films have been used for decades on fresh produce to create a semi-permeable membrane on the surface to suppress respiration, control moisture loss, and more recently, to provide a delivery mechanism for addition of functional components. Scientists at the Southern Regional Research Center (SRRC) have previously demonstrated that a thin biodegradable film can be produced from soapstock, an underused byproduct from the vegetable oil industry. After a few physical and chemical treatments, a thin film can be produced from various soapstocks (cottonseed, soybean, safflower etc.). When hydrated, it was found that the treated soapstock materials made a gel that formed an enclosing or encapsulating surface upon drying. Different hydration ratios were tested, since the initial soapstock solutions were rather viscous. To examine the potential use of an oilseed derived lipid film for extension of shelf life, different types of the oilseed-derived soapstocks were utilized to produce lipid films with different hydration ratios, and containing 0, 5, and 10 % of paraffin wax for application on ‘Camelot’ bell peppers. When stored under ambient conditions (to force maximum water loss and simulate a farmers market condition), the control bell peppers lost almost 25% weight per unit surface area (SA) in 78 h. Cottonseed film hydrated at 1:4 lost only roughly 5% moisture per unit SA after 78 h and minimized weight loss by up to 79% compared to the control. However, since a 1:4 hydration ratio remained rather viscous, 1:8 was preferred, and these cottonseed films reduced weight loss per unit SA by up to 48% during storage. Safflower-derived soapstock film resulted in the least effective water retention of the films and ratios tested, with roughly 21 to 25% reduction in weight loss per SA compared to controls. Safflower was higher in unsaturated fatty acids, which are less efficient to control moisture migration, because they are more polar than saturated lipid materials. Addition of wax to the cottonseed-derived films decreased slightly the water vapor permeability, similar to previous reports in the literature. A statistical treatment, analysis of variance (ANOVA), for the test data supported the conclusion that the oilseed-derived lipid films significantly reduced moisture loss across the produce epidermis. Further tests are needed to determine efficacy on fresh-cut produce. The preparation methods and the chemical analysis of the raw materials for the lipid film will also be presented.